1. Field of the Invention
The present invention relates to an image reading device such as an image scanner.
2. Description of the Related Art
Recently, a multifunction peripheral device has been developed. The single multifunction peripheral device can perform many functions, such as a printer function, a facsimile function, a scanner function, and a copy function. The multifunction peripheral device is therefore convenient to be used as a peripheral device for a computer.
The multifunction peripheral device is provided with an image scanner. The image scanner includes: a lamp (scanner light source) for irradiating an original document with light; and a charge coupled device (CCD) for picking up light reflected from the original document. The CCD has a plurality of light conversion elements aligned in a line. Each light conversion element in the CCD outputs a voltage with its value corresponding to the intensity of the received light. The value of the voltage therefore represents a corresponding pixel on the original document. The voltage value (voltage data) is then converted into numeric data representing an image read from the original document.